Technical Field
The present invention concerns a method of operating a wind turbine or wind power installation and a corresponding wind power installation.
Description of the Related Art
Methods of operating a wind power installation have long been known. Thus it is for example usual for wind power installations to be operated on the basis of a predetermined power characteristic which depends on the wind speed. In the case of wind power installations with rotor blades involving an adjustable rotor blade angle—generally also referred to as the pitch angle—that can also be adjusted to implement the respectively desired operating point of the wind power installation.
Such methods of operating a wind power installation however can encounter their limits if unforeseen or unusual circumstances occur such as for example icing on parts of the wind power installation. A particular problem in that respect is represented by icing of the rotor blades. Such icing causes problems because it can result in ice dropping off the rotor blades, which is dangerous for people who are below the rotor blades. The danger of such dropping ice can be increased if the wind power installation should continue to be operated in that condition.
Another problem with icing on the rotor blades is that the properties of the wind power installation are altered and regulation of the installation can be disturbed thereby. In addition, depending on the respective amount of ice formation on the wind power installation, in particular on the rotor blades, there is the risk of damage to the wind power installation.
Methods are known which try to detect ice formation on the rotor blades in order then to stop the wind power installation and shut it down to protect it. In addition, the attempt can be made to remove the ice, in the stopped condition of the installation. DE 103 23 785 A1 describes a method of detecting ice accretion.
A problem in that respect is that of reliably detecting ice accretion. Because safety aspects involve a high and usually the highest priority, shut-down of the installation is often already effected when there is a suspicion of ice accretion. That can result in unwanted and, considered objectively, unnecessary wind power installation stoppage times. Depending on the respective erection site that can add up to considerable economic losses.